Vehicle locator key fob with range and bearing measurement

ABSTRACT

An apparatus and method of determining bearing and distance measurements between a mobile device and an object using Rf based measurements. The mobile device communicates with a control in the object to determine the relative bearing between the mobile device and the object with respect to magnetic north and, optionally, the distance between the mobile device and the object. An indicator on the mobile device aid in directing s the user of the mobile device toward the object as the mobile device is moved relative to the object. The mobile device can be a key fob and the object can be a vehicle.

BACKGROUND

The present invention relates, in general, to object locator apparatusand methods and, also, to wireless vehicle key fobs for remotelyactivating vehicle control functions.

The difficulty of finding a vehicle in a large parking lot, at shoppingcenters, sporting or music events, multi-level parking structures, etc.,is a common problem experienced by all drivers on a regular basis. Longrange key fobs have historically been used to activate a vehicle hornand exterior lights which can alert a driver to the vehicle location viaaudible and/or visual cues. This approach works well if the driver iswithin hearing or visual range of the vehicle and there are noobstructions or structures which would interfere with hearing or seeingthe vehicle. This method does, however, create a nuisance in the form ofnoise pollution and possible embarrassment to the driver since manypeople could also hear the horn.

It has been proposed to incorporate a GPS receiver and a high accuracycompass into a key fob to facilitate determining the location of aparked vehicle with respect to the key fob location. This approach,however, has a significant cost and size/weight increase to the key fobfor the GPS and compass components.

SUMMARY

A mobile object locator key fob with range and bearing measurements isdisclosed.

In one aspect, a method for determining the location of an object by aremote, mobile apparatus comprises the steps of generating a bearingsignal from the object with respect to magnetic north, receiving thebearing signal by the mobile apparatus, determining by the mobile devicethe relative bearing between the mobile device and the object, andproviding direction information, including the relative bearing to theuser of the mobile apparatus to aid in directing the user to the object.

The method can also include the step of updating the directioninformation provided to the user of the mobile apparatus as the mobileapparatus is moved relative to the object.

The method may also include the step of determining distance between themobile device and the object, and the step of providing directioninformation to the user may include providing a relative distancebetween the mobile apparatus and the object.

An object remote location apparatus includes a control coupled to atransmitter and a receiver and adapted to be mounted on an object totransmit and receive wireless signals with respect to a remote mobiledevice, a mobile device having a transmitter and a receiver and oneinput member carried on the mobile device for activating an objectlocation determining sequence between the mobile device and the controlto aid the user of the mobile device to locate the object.

An antenna, responsive to the control generates an angularly rotatingsignal containing a signal angle information relative to magnetic north.The mobile device is operative to detect the angularly rotating signaland to decode the signal angle information in the rotating signal todetermine a relative bearing to magnetic north between the mobile deviceand the object.

The mobile device includes an indicator carried on the mobile device forproviding direction information including at least the relative bearingto the user of the mobile device to provide the location of the objectrelative to the mobile device.

BRIEF DESCRIPTION OF THE DRAWING

The various features, advantages, and other uses of the presentinvention will become more apparent by referring to the followingdetailed description and drawing in which:

FIG. 1 is a pictorial representation of a vehicle key fob for locatingthe vehicle using range and bearing measurement;

FIG. 2 is a schematic diagram of the components of the key fob shown inFIG. 1;

FIGS. 3A and 3B are plan views of the key fob having alternateindicators or displays;

FIG. 4 is a schematic diagram of the components of the remote keylessentry control and antenna;

FIG. 5 is a pictorial representation of the bearing determination of thekey fob and remote keyless entry control;

FIG. 6 is a flow chart showing the major steps in the range and bearingmeasurement method; and

FIG. 7 is a pictorial representation of the use of the key fob withrange and bearing measurement to assist a vehicle driver in locating thevehicle.

DETAILED DESCRIPTION

Referring now to the drawing, and to FIGS. 1-4 in particular, there isdepicted a vehicle 10 having a remote keyless entry or RKE apparatus 12mounted therein. A wireless key fob and transmitter 14 is associatedwith the RKE 12 and is identifiable by a unique frequency match toenable only the fob 14 to transmit signals to the RKE 12 which arerecognized by the RKE 12 as being valid for vehicle control functions.

As shown in detail in FIG. 2, the fob 14 includes a control 20, whichmay be a processor based control executing a control program stored in amemory 21. One or more input members or buttons 22 are mounted on thehousing 24 of the fob 14. The input members or buttons 22 are associatedwith a particular vehicle function, such as locking or unlocking thevehicle doors and/or trunk or hatch, lowering the vehicle windows,remotely starting the vehicle engine, flashing the vehicle horns and/orlights, etc. An indicator 26, such as an LED display 27 shown in FIG.3B, or one of more illuminatable devices, such as LEDs 28A, 28B and 28Cshown in FIG. 3A, may also be mounted in the fob housing 24 to displayvehicle status or button 22 selection information.

It will be understood that the shape of the fob housing 24, the numberand functions designated by the buttons 22, and the type and shape ofthe optional display 26 can have any configuration.

A power supply 30 is contained in the housing 24 for powering thecomponents of the fob 14 as shown in FIG. 2. A transmitter or atransmitter/receiver, transceiver or transponder 32 is mounted in thehousing 24 for transmitting a data signal generated by the control 20 inresponse to depression or activation of one of the buttons 22 through anantenna 34. The transmitter 32 has a frequency of operation between 300MHz to 915 MHz, for example only.

The user depresses or activates one of the buttons 22 associated withthe desired vehicle function that the user wishes to initiate. The inputsignal from the button 22 wakes up or activates the processor in thecontrol 20 which outputs a data stream to the transmitter 32. The datastream may include a data preamble, the actual vehicle function command,i.e., unlock vehicle doors, etc., an optional rolling code for vehicleto vehicle security, and possibly one or more check bits. This signal issent by the transmitter 32 through the antenna 34 to the RKE 12 where itis received by a receiver 40 through an antenna 42. The signal isdemodulated by a vehicle access controller 44 which can also be amicroprocessor based controller 44. The controller 44 outputs a signalto a vehicle function control device or to a vehicle body computer whichimplements the desired vehicle function.

It will be understood that the description of the fob 14 and vehicle RKE12 for remotely controlling various vehicle functions, such as lockingand unlocking doors, activating vehicle horn and/or lights, etc., is byway of example only as the following description of a method andapparatus for determining range and bearing measurement between thevehicle and the key fob can be implemented without remote vehiclecontrol functions provided by the fob and by the vehicle RKE.

In one aspect, the control 20 of the fob 14 and the RKE 12 in thevehicle or stationary object are programmed with appropriate transmitand receive capabilities to perform both relative bearing or angle andrange or distance measurement using radio frequency signals. Therelative bearing or angle and the range or distance measurement useprocessing techniques similar to Automatic Direction Finder (ADF) or VHFOmni-Range (VOR) using a radio frequency transmitter on a stationaryobject to be located, such as the vehicle 10, which broadcasts a uniquesignal which the mobile or remote device, such as the fob 14 in thepresent implementation, receives and analyzes to determine the relativeor absolute angle between the mobile device and the stationarytransmitter.

For example, as shown in FIG. 4, an antenna 46/47 which generates acircumferential, rotating signal carrying absolute or relative angle ofthe antenna 46 relative to local magnetic north. The antenna 46 may be aphase array antenna continuously generating rotating orcircumferentially oriented signals, such as signals A, B, and C in FIG.5, which carry relative angle or hearing information of each signal A,B, or C, relative to magnetic north 48 as detected by compass or otherequipment used to measure the earth's magnetic field at the location ofthe antenna 46. The signals A, B, and C, respectively carry differentangle information as each signal is generated by the antenna 46.

As shown in FIG. 5, depending on the position of the fob 14 relative tothe antenna 46 which is mounted on the vehicle 10, the fob 14 willdetect and receive one of the angular rotating signals A, B. and Cgenerated by the antenna 46. The control 20 of the fob 14 decodes theangular signals A, B, and C, and determines an angle or bearing betweenthe fob 14 and the vehicle 10 on which the antenna 46 is mounted.

The control 20 in the fob 14 also can determine approximate distancebetween the mobile device of fob 14 and the vehicle 10 by signalpropagation time delay of an Rf signal between the mobile device 14 andthe vehicle 10 or by other means, such as the relative signal strengthof a return signal from the RKE 12 in response to a distance requestsignal from the fob 14.

As shown in FIG. 6, for power conservation purposes, the vehicle orobject locator sequence would only be enabled when the vehicle ownerinitiates it via depression of one of the input members 22 on the fob 14as shown by step 50 in FIG. 6. The object locate sequence would beactive only for a set time as established by a time window in step 52.The fob 14 sends an initiation signal in step 52 to the vehicle RKE 12which activates the antenna 46 of the vehicle RKE 12 in step 54. In thisstep, the antenna 46 generates the circumferentially spaced continuouslyrotating angle containing signals A, B, and C, etc., as shown in FIG. 5.One of these signals A, B, C, etc., is received and decoded by the fob14 in step 56. The control 46 in the fob 14 uses this angularinformation to determine the relative angle or bearing between the fob14 and the vehicle 12 with respect to magnetic north in step 58.

Simultaneous with the activation signal in step 52 or as an independenttime space signal, the fob 14 transmits a distance measurement signal instep 60 to the RKE 12. Immediately upon receiving the distancemeasurement signal, the vehicle access controller 44 in the RKE 12retransmits a return signal via the transmitter 40 and antenna 46 whichis received by the fob 14 in step 62. The time propagation delay betweenthe start of transmission of the distant signal by the fob 14 in step 60until the return signal is received by the fob 14 in step 62 is used bythe control 20 in the fob 14 to determine the approximate distancebetween the fob 14 and the vehicle 10 in step 64, taking into accountthe propagation delay of an Rf signal in air and the short signalprocessing time required by the RKE 12 upon receiving the distant signalfrom the fob 14 before the RKE 12 retransmits a return signal to the fob14 in step 64A.

Alternately, the fob control 20 measures the return signal strength instep 64B and compares it to pre-established distance versus signalstrength relationships to determine the approximate distance between thefob 14 and the vehicle 10.

The fob 14 can provide the bearing and/or range information to the userof the fob 14 in different ways in step 65. In one aspect shown in FIG.3A, one or more illuminatable devices, such as LEDs 28A, 28B, and 28Care mounted on the housing 24 of the fob 14. Each LED 28A, 28B, 28C maybe a different color or the centrally located LED 28B in the illustratedexample of three LEDs, 28A, 28B, or 28C can be one color to indicatethat the user is following a direct path to the vehicle, and the otherLEDs 28A and 28C located to the left and right of the central LED 28Bcan be used to indicate that the user is diverging from the directbearing or path to the vehicle 10. This use of the LEDs 28A, 28B, and28C, which also can include flashing signals from one or more of theLEDs 28A, 28B, and 28C, with the flash cycle indicative of theapproximate distance, whether increasing or decreasing, between the fob14 and the vehicle 10 to guide the user via a “cold, warm, hot” deadreckoning-type locator system.

Referring briefly to FIG. 7, the fob 14, after determining the bearingand distance between the fob 14 and the vehicle 10, determines a directpath shown pictorially by reference number 70 to the vehicle 10. As longas the user of the fob 14 follows this path 70, only the LED 28B wouldbe lit. As the LED 28B could flash at a periodic rate which decreases intime as the distance between the fob 14 and the vehicle 10 decreases.The flash rate of the LED 28B could also decrease if the user of the fob14 were to move away from the direct path to the vehicle 10 into thearea denoted by reference number 72 in FIG. 7.

The LEDs 28A and 28C would be illuminated by the control 20 of the fob14 when the user diverges from the path 70, while still decreasing thedistance between the fob 14 and the vehicle 10, by moving into the areas74 and 76 to the left and right, respectively, of the direct path 70.

It will be understood that the direct path 70 could also cover a slightdiversion sector area 78 which is still close enough to the direct path70 to be useful in leading the user of the fob 14 to the relative areaof the vehicle 10.

In another aspect shown in FIG. 3B, a visual graphical display 27 on thefob 14 can include display 27, such as an LCD display, for example,which is capable of displaying graphic representations, such as the maincompass points, north, south, east, and west, all denoted by referencenumber 80, and a line depicting the direct path 70 from the location ofthe fob 14 denoted at a center point 82 on the display 27 to the vehicle10. The relative angle of the direct path 70 to one of the main compassdirections 80 would be changed by the control 20 in the fob 14 if theuser were to turn in a circle or otherwise diverge from the direct path70 to the vehicle.

The display 27 can also include a flashing signal whose flash rate isproportional to the changing distance between the fob 14 and the vehicle10.

The fob control 20 will continue to update the bearing and/or rangeinformation as the user moves relative to the vehicle 10 as long as thetotal time of the locate sequence is within the total time establishedby the locate sequence time window in step 52. The total time is checkedin step 66 and the locate sequence terminated if the total preset timehas been exceeded, or continued as explained above if time remains inthe time window.

The use of Rf based bearing and distance measurement techniques in a fob14 and the vehicle RKE controller 12 results in a low cost, light andsmall fob whose functional range is limited only by the effective Rfrange of the system. The use of Rf signals for bearing an arrangedmeasurement enables the fob 14 to be used in locating the vehicle 10 inranges up to one mile or more in open air as well as at shorterdistances in covered structures, such as parking garages.

In addition, the range and measurement features described above may beincorporated into existing configurations for vehicle fobs 14 andvehicle RKE controls 12 without requiring additional space, complexcomponents, or external ground or satellite infrastructure.

1. An object location apparatus comprising: a control adapted to bemounted on an object to transmit and receive circumferential, rotatingwireless signals with respect to a remote mobile device; a transmitterand a receiver coupled to the control; the mobile device having atransmitter and a receiver; and one input member carried on the mobiledevice for activating a location determining sequence in the mobiledevice and the control to aid the user of the mobile device in locatingthe object.
 2. The apparatus of claim 1 further comprising: an antenna,responsive to the control, for generating said angularly rotating signalcontaining signal angle information relative to magnetic north; and themobile device operative to detect the angularly rotating signal and todecode the signal angle information in the angularly rotating signal todetermine a bearing relative to magnetic north between the mobile deviceand the object.
 3. The apparatus of claim 1 further comprising: themobile device operative to determine an approximate distance between themobile device and the object.
 4. The apparatus of claim 3 wherein: themobile device determines the distance by determining the time delay of asignal transmission from the mobile device to the object and a returnsignal from the object to the mobile device.
 5. The apparatus of claim 3wherein: the mobile device determines the distance of determining thesignal strength of a return signal from the object to the mobile device.6. The apparatus of claim 1 further comprising: an indicator carried onthe mobile device for providing direction information including at leastthe relative bearing to the user of the mobile device to provide thelocation of the object relative to the mobile device.
 7. The apparatusof claim 6 further comprising: the mobile device operative to update thedirection information as the mobile device is moved relative to theobject.
 8. The apparatus of claim 6 wherein the indicator comprises: avisual display carried on the mobile device and providing geographiclocation information including a bearing path between the mobile deviceand the object.
 9. The apparatus of claim 6 wherein the indicatorcomprises: at least one illuminatable element carried on the mobiledevice for indicating when the user of the mobile device is moving on asubstantially direct path to the object as the mobile device is movedrelative to the object.
 10. The apparatus of claim 9 wherein the atleast one illuminatable element comprises: a plurality of light emittingdiodes carried on the mobile device for indicating relative separationof the user of the mobile device from a direct path between the mobiledevice and the object as the mobile device is moved relative to theobject.
 11. The apparatus of claim 1 wherein: the object is a vehicle;and the mobile device is a portable key fob.